Spatial light modulators (SLMs) are devices used to control the distribution of light in an optical system. SLMs are typically configured as one or two-dimensional arrays of individually addressable optical elements, representing pixels of an image. These elements modify either the amplitude or the phase of the light distribution within the optical system.
SLMs can be divided into various types, including an electro-optic, magneto-optic, liquid crystal, and deformable mirror devices. These different types may be further characterized according to whether they are suitable for amplitude modulation, phase modulation, etc.
SLMs and their applications are described in various patents and patent applications. An example visual display system having a spatial light modulator with individually controllable elements, wherein each element is capable of producing an individual light beam directed toward a display surface, is described in U.S. Pat. No. 5,214,420, entitled “Spatial Light Modulator Projection System with Random Polarity Light.” An example method and structure for providing system control to a spatial light modulator display is described in U.S. Pat. No. 5,254,980, entitled “DMD Display System Controller.” The entireties of both patents are incorporated by reference herein.
Many applications involve using SLMs in display systems, where an SLM optics unit replaces a raster scan unit. These are image output generation systems, in which the SLM receives input data in the form of electrical signals for the purpose of determining how light is to be reflected by its pixel elements as light output to a display screen, printer, or other such equipment. Thus, SLMs are traditionally used to transform an electrical signal to light patterns, and thereby generate an image output.
Conventional means for creating an electrical output signal from a captured input image as an electronic signal, as opposed to recreating an output image from an input signal, do not typically involve the use of SLMs. In many applications the light receiving device is a photosensor array, in which an array of photosensor elements is used to differentiate pixels of the image. Each element of the array generates a signal corresponding to a pixel point of the image. This signal can be transmitted, digitized, or otherwise processed for reconstitution into an image at a desired time and place.
A system for capturing an input image using SLM optics with a single-element sensor is described in U.S. Pat. No. 5,212,555, entitled “Image Capture with Spatial Light Modulator and Single-Cell Photosensor”; the entirety of which is incorporated herein by reference. In this arrangement, as each pixel element in an SLM array is individually switched into a light reflecting position, light from the respective pixel is directed to a sensor which generates a signal proportional to the light associated with that pixel element, the result being a series of individual pixel output signals, together representing an input image frame. The entirety of that patent is incorporated by reference herein.
Such systems do not, however, provide image input and image output capability in a same shared resource system.